Like many other villages in the area, Castlecary has Roman heritage. The route of the Antonine Wall passes close to the village. A Roman camp existed at Castlecary, first constructed around the year AD 80, possibly during the fourth campaign season of governor Gnaeus Julius Agricola. Excavated in 1902, the Roman fort was probably devastated by the 2nd century.

About the village

There is little in the village today, save for the local Castlecary House Hotel. The nearby Castlecary brickworks in Allandale at one stage provided local employment, but the site is now derelict and awaiting redevelopment. One suggested use of this site has been the construction of a new "park and ride" railway station, to be called 'Allandale'. It had been previously suggested that the station be called Castlecary, but representations were made to the scheme's sponsors not to call it this given the existence of a Castle Cary Station in Somerset and the potential for confusion between the two.

There was nevertheless previously a Castlecary railway station, now long since closed. This was the site of a major rail accident on 10 December 1937, when two trains collided with one another. The accident cost the lives of 35 people, with a further 179 injured.

Castlecary also lends its name to a viaduct which crosses the A80. These are commonly known as the "Castlecary Arches".